One vertex per element, one color per generator, with an edge from x to x·s.
(3,7)(6,8)(10,13)(11,15)(17,18,21,19)(20,23,24,22)(25,26)(27,32)(28,34)(29,37)(30,31)(33,38)(35,36)(39,40)(2,5)(6,8)(11,15)(14,16)(26,31)(27,34)(33,37)(35,40) involution — undirected(1,2,4,5)(3,6,7,8)(9,10,12,13)(11,14,15,16)(17,19,21,18)(20,23,24,22)(25,27,30,34)(26,32,31,28)(29,35,38,40)(33,39,37,36)(1,3,4,7)(2,6,5,8)(9,11)(10,14)(12,15)(13,16)(17,20)(18,22)(19,23)(21,24)(25,28,30,32)(26,27,31,34)(29,36,38,39)(33,35,37,40)(25,29,30,38)(26,33,31,37)(27,35,34,40)(28,36,32,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.